The purpose of this grant is to study the physiological control of the larynx as the source function for speech. We are interested both in the fine structure of control of the shape and repetition rate of the glottal pulse, perceptually described as pitch and voice quality variation, and the slower adductory and abductory forces acting on the vocal folds to control voicing and devoicing. The respiratory and muscular forces are to be studied by the techniques of transillumination and fiberoptic viewing of the folds, aerodynamic measures and electromyography of the extrinsic and intrinsic laryngeal muscles. There will be parallel studies of normal and deaf speakers and stutterers.